Process of manufacturing luminous tubes and apparatus for carrying them out



g 3 9 1932- R. R. MACHLETT 4,

PROCESS OF MANUFACTURING LUMIN OUS TUBES AND APPARATUS FOR CARRYING- THEM OUT Filed Aug. 17. 1928 T ig; 1

f To qns GUPPLY Fun . or molsture,

' RAYMOND R. MACI-ILETT, onrivnwzxonx mvq iessmivoniro 'RAINBOWaLIGHT, incl; or 4" LONG .ISLANDJCITYmNEWXYORK, A coBrnRArmN on new Yon-K Patented Aug. 30, 1932 "rnocnss :01? MANU AG URI G}Luminousmnnnsllmn .Anmiwe Easements q V 'lHEM U;T..,: -'e

' ture, and

i Application mea'Au ustliv, 1928f serial 116*.1360 341 7 My" present invention relates to the'proce'ss H of manufacturing luminous. electrical; dis' charge tubes whichcontainfa rarefied atmos-. phere comprising an inert gassu'ch acldedfor the purpose; among e others,**of creasing the range of colors; In the manufacture of such'tubes it is1essential to remove every possibleitraceof gas" not only from. the interior butfrom the walls 'and electrodesg beforeith'e" rare gas or the mercury is injected. 5 For commercial reasons it isalso very desirame-mperform the operations of exhaustingpurifying and filling the tube in the simplest,- quickest and most convenient Way,

sity forfurther aging or' seasoningzand tofl perform these operationsnpon' several tubes at the'same saving of time in manufacturefover thecus tomary practice of processing eachtube sepag rately; i

To accomplish a process and the apparatus, for-performing it which permits of thesimultaneous heating, exhaustingfilling of a number ofl'u'minous tubes which is "particularly" efi'e'ctive in the'processing oftubes inlwhich mercuryand mercury vapor are; to be injected; as" well as. insulatingjacketg which may be convenient a rare gas orcornbinationof raregases. f This it is the subject of this invention.

In" orderthat my iliVGIliJlOIl may be clearly understood, "attention ,is directed to the' -accompanying drawing as neon- -2v2. or argon or a comblnation ofsuch-gase'sftogusuale lectrodejwhlch a small quantity of mercury vapor 11s these resultsiif fiefi i iied at -about the cente t m g fi' 1 Portion ,ofe'ach tube v1 i P o with deg:

1 suchas by'means of gas d partition-11. It is also 7 Fig. 1 isa perspective view'of a suitable oven'for processing the tubs,"in. which three.

tubes are shown, lifted to disclose the interior. 7

Fig. 2 is a side elevation on a larg'erlscale showing a single tube'inprocesso'i manufac- Fig..3 is a perspe manner 'n which a single mercury reservoir may be used in ,simultaneously processing several tubes, as'inFig. 1.

In all of these vlews corresponding parts the front of thdoven beingservedi' straight central portion and enlarged ends- In each' of the enlargedends is -the 3 oftlre'm -are mountedaside by side as shown show threeof these tub 1' and 'provided with tubul'ations 3' or manifold and-' supported by. hangers '5' within a suitable *oven; 6. For the-purpose of By? -th1is-simultaneously] processing a -plu'--- or pacity 'iof thenven and reduce the time re- *without'the necese quired to" performthe necessary operations-L v tofth'e exhaust pump which? v may: be. ofthe usualtype for. producing the time, thereby securing a moregnecessaryhigh' vacuumr- Tube 4:, -at some' uniform product andachieving a-subs'tantial P Outside offthe oven is j oined by'a branch tu-beqleadirigto .gas,-witlr which-the tube is' ultimately tobe pending ,portion 8' which serves- 1 as v a 'reser- --voir, for mercury of"ach"tubulationfissurrounded by a heat/5 'Tlie-tubiilation 3 whichispreferably posi j The-depending portion 8 1y made of asbestospaper rolled to fornr'1-=a process and the apparatus for'perfoi'ming'; heavy walledsleeve;

6 is heated inany suitable way,

-' 'ets 10 positioned be! "The oven low a perforate equipped can a door 12 which is provided with one ormore mica covered openings-13 so that the tubes within the oven maybe ob- The'ele'ctrodes o1? the tubes are connected tea-suitable source ofelectriccurrent by com ductorslk'leading t0 the secondary 15' of transformer, the primary 16 of which is in ctive *viewillu'str a-ting the are represented bythe same numerals.

circuit with a suitable source of alternating electrical connections and the conductors;

v current-17 Each of thetubes has similar may, obviously, be connected in'multiple'with a single secondary. Assuming "that the tubes are supported In-'proc e'ssingthe improved tubes anumber illustration I 9 within the oven as shown in Fig. 1, the process is carried out as follows:

The asbestos insulating sleeves 9 aresaturated with water. and placed, around the lower part. of the tubulations 8. The oven;

ducedall of theelectrodes of all of the tubes are broughtto a red heat by the passage of 7 drive off gases occluded within the electrodes.

a heavy current therethrough in order to The current employed forthis'purpose'is' substantially greater than'the normal current with whichthe tube is designed to operate;

Thus the normal current in operation will not I tendto drive off. residual impurities. I During the next stage of the process the temperature of the oven is slowly raisedto a degree sufficiently high to drive of? gases,

occluded within the walls of the tubes, which temperature ishigher than that at which the mercury within'the depending portion 8 of the tubulation 3 would vaporize were it not, for the water saturated asbestos insulating sleeve 9 which surrounds each tubulation.

The oven temperature duringthis stage may. ior example be irom450 to 475? Centigrade. I

have foundthat at thesete'mperaturesa small amount of alkali'metal, which is always held ina free state in-the'glass walls of the tubes, is vaporized and permeatesthe interior of the.

tubes,-acting as a purgingagent for the interior ofthe tube.

After this is accomplished the heat is turned ofi', the oven door opened and the in-; sulating sleeves removed. The oven is then closed again and thetemperature raised sufficiently to vaporize the mercury, the vapor of which will pass into and throughout the tube. Only the temperature necemary to pro:

heat is then again. turned ofi. After a short time the oven door. is again opened; and the oven temperature is allowed to drop to below 250 after which the electrodes are-again heated to a :red heat and the pumping continued until the highest possible vacuum has been obtained. Then the tube is flushed out with a quantity'of pure gas, the pump shut off and pure gas admitted to the desiredpressure. The tube is then sealed off at 18. A

small amount of the mercury in portion 8 of tubulation 3 is then poured into eachtube and it is then sealed off from the tubulation 3. The tube is now ready for use without further aging or seasoning.

Although I have referred to the tubes as: having interior electrodes it will be seen that ifthey are provided with exterior electrodes instead they may be processed in the same way and with the same'advantages as to at. 3 cllity of operation and saving of time.

A modification of the above arrangement is shown in Fig. 3 wherein a single tubulation or reservoir for mercury has been substituted for the individual tubulations associated wlth jacket is required.- Otherwise, the process .rcmainsunaltered.

It will be seen that a number of tubes can I be processed at once and the mercury vapor injected therein coincidentally with r the cleansing process, thus doing away with spe- V necessary. 7 V

l'Q V QW de ribed my lnvention what I claim 1s cial. treatments which have been considered said; tube, and tubulation within a heating 1. The method ofproces'singf a luminous I tube of'the class described, said tube being "provided withan auxiliary tubulationfcon-I tainingjmercury which consists in placing.

oven, ininsulating the tubulation from the effects of heat, in heating the tube to a tem perature higherthan, that at which mercury vaporizes, in removing said protecting means from said tubulation and subjecting it to heat so that the mercuryzis' vaporized and diffused; throughout the tube.

gases therefrom, in, heatingthe-tube toremove occluded gases therefrom, said tubulation being insulated from the source of heat,

in removingsaid-insulation from said'tubula -tien, in heating the tubulation to vaporize; themercury therein and to cause thevapor duce vaporization will. be required. The,

to pass-into and diffuse through thetube;

ing said tubulations fromthe effect of heat, insimultaneously heating all of said tubes to a temperature higherthan that at which mercur vaporizes, in removing the insula 2. -:T'he method. of processinga luminous; tube of the classdescribed provided with ani'9 auxiliary rtubulationf. containing mercuryv which consists inplacing said tube andtubu- :latio'n within a heating-ovem'increating a r tion from said tubulations and. in heating u said tubulations to a temperature atwhich the mercury therein will vaporize.

- 4. Themethod of simultaneously process-- ing a multiplicity of luminous tubes' of the class described, which consists in connecting each of said tubes respectively to auxiliary tubulation containing mercury, in connecting saidtubes to a common manifold, in placing saidtubes, tubulations and manifold in a heating oven, in connecting said manifold to a vacuum pump, in insulating said tubulations from the effects of heat, in creating a partial vacuum therein While heating said tubes, in passing a heavy electrical current between the electrodes of the tubes to heat them to incandescence for the purpose of freeing them from impurities, in raising the temperature of the tubes to a degree above that at which mercury vaporizes, in removing the insulation from the tubulations, in heating the tubes and tubulations until the mercury vaporizes and the vapor diffuses through the tubes, in reducing the temperature of the oven, in again heating the electrodes to red heat by the passage of current between them, in exhausting the tubes to a high vacuum, in flushing the tubes with a quantity of the,rare gas with which they are to be filled, in filling the tubes with the rare gas to the desired pressure, in sealing olf the tubes from the common manifold, in pouring into the tubes a small quantity of unvaporized mercury from its tubulation and in sealing off the tubes from the tubulations. V

5. The method of processing a multiplicity of luminous tubes of the class described which consists in connecting said tubes in multiple to a manifold, in connecting to each of said tubes a reservoir containing mercury, in insulating said reservoirs from the-effects of heat, in placing said tubes, manifold and reservoirs within a heating oven and connecting said manifold to a vacuum pump, in are ating a partial vacuum within said tubes, in heating said electrodes to a red heat to free them from impurities by passing a heavy electric current through them, in heating the tubes to a temperature of approximately 450 centigrade for approximately ten minutes, in removing the insulation from the mercury reservoirs, in raising the temperature of the tubes and the reservoirs to a temperature at which the mercury within the reservoirs will be partially vaporized and diffused through the tubes, in reducing the temperature of the tubes to approximately 250 centigrade and again heating the electrodes to red heat by the passage of current at this oven temperature, in creating a high vacuum within said tubes, in flushing out the tubes with a quantity of the pure gas with which they are to be filled, in filling the tubes with pure gas to the desired pressure, in sealing off the tubes from the manifold, in pouring into each oven is raised above that at which mercury vaporizes and means for admitting into the tubes a rare gas of the atmosphere.

7 Means for vaporizing mercury contained within an auxiliary tubulation communicating with a luminous tube of the class described, comprising an oven in which the luminous tube and tubulation are placed, a sleeve of heat insulating material surrounding the tubulation and adapted toinsulate it from the heat when the oven is raisedto a temperature higher than that at which mercury vaporizes said sleeve being subsequently removed to expose the tubulation to the heat of the oven.

8. Means for vaporizing mercury contained within an auxiliary tubulation communicating with a luminous tube of the class described, comprising an oven in which the luminous tube and tubulation are placed, a removable sleeve of heat insulating material surrounding the tubulation and adapted to insulate it from the heat when the oven is raised to a temperature higher than that at which mercury vaporizes said sleeve being subsequently removed to expose the tubulation to the heat of the oven.

RAYMOND R. MACHLETT.

tube a small quantity of the unvaporized mercury from its reservoir and in sealing off said tubes from said reservoirs.

6. Means for simultaneously processing a multiplicity of luminous tubes of the class described comprising a heating oven in which the tubes are suspended, a common manifold connecting the tubes in multiple with a vacuum pump, an auxiliary tubulation containing mercury communicating with each tube, means for insulating said tubulations from the effect of heat when the temperature of the 

